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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#pragma once
#include <memory>
namespace document {
class Document;
class DocumentTypeRepo;
/**
* FieldSet class. Represents a subset of fields in a document type.
* Note that the document id is counted as a field in this context,
* but referenced by the special name "[id]"
*/
class FieldSet
{
public:
enum class Type {
FIELD,
SET,
ALL,
NONE,
DOCID,
DOCUMENT_ONLY
};
using SP = std::shared_ptr<FieldSet>;
using UP = std::unique_ptr<FieldSet>;
virtual ~FieldSet() = default;
/**
* @return Return true if all the fields in "fields" are contained in
* this field set.
*/
virtual bool contains(const FieldSet& fields) const = 0;
/**
* @return Returns the type of field set this is.
*/
virtual Type getType() const = 0;
/**
* Copy all fields from src into dest that are contained within the
* given field set. If any copied field pre-exists in dest, it will
* be overwritten.
* NOTE: causes each field to be explicitly copied so thus not very
* efficient. Prefer using stripFields for cases where a document
* needs to only contain fields matching a given field set and can
* readily be modified in-place.
*/
static void copyFields(Document& dest, const Document& src, const FieldSet& fields);
/**
* Creates a copy of document src containing only the fields given by
* the fieldset. Document type and identifier remain the same.
* See comment for copyFields() for performance notes.
* @return The new, (partially) copied document instance.
*/
static std::unique_ptr<Document> createDocumentSubsetCopy(const DocumentTypeRepo& type_repo, const Document& src, const FieldSet& fields);
/**
* Strip all fields _except_ the ones that are contained within the
* fieldsToKeep fieldset. Modifies original document in-place.
*/
static void stripFields(Document& doc, const FieldSet& fieldsToKeep);
};
}
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